The present disclosure relates to a heating unit, a fixing device, and an image forming apparatus.
An electrographic image forming apparatus includes a fixing device that thermally fixes toner on a medium.
For example, a heater of the fixing device is proposed. The heater has a circuit board that extends in a direction orthogonal to a conveying direction of a recording material, heating resistors that are formed on the circuit board with a long pattern in a longer side direction of the circuit board, and a first conductive part and a second conductive part that are formed in a longer side direction of the heating resistor on respective both sides of a shorter side direction of the heating resistor. The heating resistors generate heat when an electrical current flows between the first and second conductive parts in the conveying direction of the recording material. The first conductive part has divided conductors that are plurally divided in the longer side direction. In the fixing device, electrical power is independently supplied to each heating resistor that corresponds to a divided conductor so as to restrain temperature rising at a non-sheet passing region through which the recording material does not pass.